Cross-SIM calling using network slices with QoS

Abstract

A user equipment (UE) (102) uses a cross-subscriber identity module (cross-SIM) call by establishing a network tunnel (122) between the UE and a first cellular network (104-1) via a wireless connection (116) with a second cellular network (104-2). The wireless connection with the second cellular network is used as part of a network slice (118) between the UE and the second cellular network having one or more quality of service (QoS) features suitable for conducting the UE's call. Thus, QoS support for the link between the UE and the second cellular network contributes to an overall QoS level of the call between the UE and the first cellular network.

Description

[Background technology]

[0001] Mobile phones, tablet computers, and other wireless communication devices are often configured with two or more subscriber identity modules (SIMs), each used to support a separate cellular connection with a corresponding cellular network. For example, one SIM may be used to establish a subscriber's cellular connection for voice services with one mobile network operator, while another SIM may be used to establish a different subscriber's cellular connection for data services with another mobile network operator. In another example, one SIM may be used for a user's primary or default mobile subscription, while the other SIM is used to provide an alternative subscriber connection when the wireless communication device can no longer connect to the network provided by the primary mobile network operator, i.e., when the wireless communication device is "roaming" outside the range of the primary mobile network operator.

[0002] Some wireless devices with multiple SIMs are configured to support "cross-SIM calling." In a cross-SIM call, a wireless data connection is established via a "secondary" SIM, while the corresponding voice call is carried out over a wireless data connection established using the secondary SIM, associated with the identity of the "primary" SIM and its corresponding carrier (or mobile network operator). However, in typical cross-SIM calling implementations, the wireless connection established via the secondary SIM is treated as a standard data connection and therefore does not have quality of service (QoS) features specifically suited to voice calls. Therefore, poor QoS over the wireless data connection may result in poor voice call quality during a cross-SIM call. Summary of the Invention

[0003] According to one aspect, a method for conducting a call between a user equipment (UE) and a first cellular network via a second cellular network includes implementing a network slice between the UE and the second cellular network, the network slice having at least one quality of service (QoS) feature suitable for supporting the call. The method further includes establishing a network tunnel between the UE and the first cellular network via the network slice and conducting packet communication of call data between the UE and the first cellular network via the network tunnel.

[0004] Various embodiments of this aspect may include the following, individually or in various combinations: The method further includes selecting the network slice from a plurality of network slices obtained from a second cellular network used by the UE. Selecting the network slice may include selecting the network slice at the UE based on a list of available network slices provided by the second cellular network. Selecting the network slice may further include selecting the network slice based on a comparison of QoS parameters of the call and corresponding QoS capabilities of the one or more available network slices. Establishing the network tunnel may include establishing the network tunnel based on a first subscriber identity of the UE associated with the first cellular network, and the plurality of network slices obtained from the second cellular network used by the UE may be based on a second subscriber identity of the UE associated with the second cellular network. The method may further include receiving, at the UE, an indication of the network slice to implement from the second cellular network in response to at least one of transmitting an indication regarding QoS requirements of the at least one call to the second cellular network or transmitting an indication that the call is supported by the first cellular network via the second cellular network. Establishing the network tunnel may include establishing the network tunnel based on a first subscriber identity of the UE associated with the first cellular network, and implementing the network slicing may include implementing the network slicing based on a second subscriber identity of the UE associated with the second cellular network and different from the first subscriber identity. In this example, the first subscriber identity is stored by a first Subscriber Identity Module (SIM) of the UE, and the second subscriber identity is stored by a second SIM of the UE. Establishing the network tunnel may include establishing a network tunnel between the UE and an Internet Protocol Multimedia Services (IMS) server of the first cellular network.The method may further include initiating the call at the UE by a user software application executing on the UE and providing the UE with a data interface for use in the call in response to establishing a network tunnel.

[0005] According to another aspect, a method includes performing a cross-subscriber identity module (cross-SIM) call between the UE and a first cellular network via a network tunnel between the UE and the first cellular network utilizing a network slice established between the UE and a second cellular network, the network slice being selected to provide at least one QoS feature in support of the cross-SIM call.

[0006] Various embodiments of this aspect may include, individually or in combination: The second cellular network may select a network slice based on a UE attempting to perform a cross-SIM call; The UE may select a network slice from a list of network slices obtained from the second cellular network based on QoS features supported by the listed network slices; The network tunnel may include an evolved packet data gateway (ePDG) tunnel; The call may include either a voice call or a video call.

[0007] According to another aspect, a user device includes an application processor, a radio frequency (RF) modem coupled to the application processor, at least one antenna array coupled to the RF modem, and at least one memory for storing instructions configured to operate one or both of the application processor or the RF modem to perform one or both of the methods described above in various embodiments.

[0008] The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings, in which: The use of the same reference symbols in different drawings indicates similar or identical items. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating a mobile cellular system using user equipment (UE) with cross-SIM calling utilizing network slicing to provide call QoS according to some embodiments. [Figure 2] 2 is a block diagram illustrating a hardware configuration of the UE of FIG. 1 according to some embodiments. [Figure 3] FIG. 1 is a flow diagram illustrating a method for conducting a cross-SIM call using network slices with call QoS according to some embodiments. [Figure 4] 4 is a ladder diagram illustrating an example operation of the method of FIG. 3 according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] Cross-SIM calling enables a mobile phone, cellular-enabled watch, tablet computer, in-vehicle cellular communication system, or other UE to establish a data-based voice or video call over a cellular network associated with one SIM using a data connection provided through the other SIM. However, the data connection is typically not configured to provide specific QoS features supporting voice / video calls, such as low packet loss, low latency, and low jitter, making the call vulnerable to degradation in quality. The 3rd Generation Partnership Project (3GPP®) 5G New Radio (5G NR) standard specification promulgates technology for "network slicing," a network architecture that facilitates the multiplexing of virtualized and independent logical networks (i.e., "network slices") over the same physical network infrastructure, with each network slice being an isolated end-to-end network path that can be tailored to meet the specific parameters of a corresponding application. This disclosure describes embodiments of systems and methods that leverage network slicing to provide cross-SIM calling with appropriate QoS support for the wireless data connection over which voice call traffic is routed. In at least one embodiment, when a call is initiated (either as a cellular voice service or a voice-over-data service) and a first SIM designated to handle the call is out of service (OOS) or otherwise does not have a serviceable connection to a corresponding first cellular network, but a second SIM has a serviceable connection to a corresponding second cellular network, a cross-SIM call process is initiated, in which the UE utilizes its connection with the second network to request a network slice with QoS appropriate for the voice call. In response to granting the requested network slice, the UE establishes a network tunnel with the first cellular network via the second cellular network. The first cellular network and the UE then communicate packetized call data using the established network tunnel.The network slice between the UE and the first network provides one or more QoS functions for cellular transmission of call packets between the first cellular network and the UE, such that a certain QoS level can be provided for the call while utilizing the second network, thereby providing satisfactory call quality in a manner that is transparent to the user as if the call were made directly in the first cellular network.

[0011] For ease of reference, the term "Subscriber Identity Module" or "SIM" will be used to refer to the subscriber identity of the corresponding cellular network. However, it will be understood that reference to a Subscriber Identity Module or SIM also includes other forms of representing a subscriber identity, such as a Subscriber Permanent Identifier (SUPI), an International Mobile Subscriber Identity (IMSI), and mechanisms for storing and / or representing a subscriber identity, such as a Universal Integrated Circuit Card (UICC), a Universal Subscriber Identity Module (USIM), etc.

[0012] FIG. 1 illustrates a cellular communication system 100 using cross-SIM calling with call QoS support via network slicing in accordance with some embodiments. As shown, the system 100 includes user equipment (UE) 102 and one or more cellular networks 104 (referred to herein simply as “networks”). The UE 102 may include any of a variety of electronic wireless communication devices, such as a mobile phone, a cellular-enabled tablet computer or laptop, a cellular-enabled watch or other wearable device, an automobile or other vehicle with cellular service (e.g., navigation, entertainment service provision, in-vehicle mobile hotspot, etc.). Each network 104 is connected to one or more other networks 104 via at least one packet data network (PDN) 105, such as the Internet, one or more private interconnected data networks, or a combination thereof.

[0013] Each network 104 includes a core network 106 and multiple edge networks, or radio access networks (RANs), connected via a backhaul infrastructure. Each edge network includes base stations (BSs) 110, such as base stations 110-1 and 110-2, capable of wireless communication with UEs within signal range based on one or more radio access technologies (RATs). Examples of base stations 110 include, for example, a NodeB (or base transceiver station (BTS)) for a Universal Mobile Telecommunications System (UMTS) RAT implementation (also known as "3G"), an enhanced NodeB (eNodeB) for a 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) RAT implementation, a 5G NodeB (gNB) for a 3GPP 5th Generation (5G) New Radio (NR) RAT implementation, etc. As is known in the art, the base stations 110 operate as an "air interface" for establishing radio frequency (RF) wireless connections with the UEs, and these wireless connections (or "links") serve as data and voice paths between the UEs and the core network 106 to provide various services to the UEs, such as voice services over circuit-switched or packet-switched networks, messaging services such as Simple Messaging Service (SMS) and Multimedia Messaging Service (MMS), multimedia content delivery, and presence services.

[0014] Generally, the provision of services to UEs by cellular networks is subscription-based. That is, the specific services provided by the network 104 and the manner in which those services are provided are based on a mobile subscription established by the network for the corresponding UE. Typically, each mobile subscription is associated with a corresponding unique subscriber identity, often in the form of an International Mobile Subscriber Identity (IMSI). Often, the subscriber identity is encoded on an integrated circuit (IC) card for security purposes, allowing a user to switch UEs by removing the IC card from one UE and installing it in another while maintaining the same subscriber identity. Examples of IC cards include universal integrated circuit cards (UICCs), more specifically subscriber identity modules (SIMs). In other examples, IC cards are "virtualized" by instead storing the subscriber identity and related information in a secure memory location within the UE itself. For ease of reference, an example implementation of a subscriber identity stored on and represented by a SIM will be described. However, the techniques described herein are not limited to these examples, and therefore, unless explicitly stated, references to a SIM for purposes of subscriber identity equally apply to other forms of representing the subscriber identity.

[0015] Because the services offered by operators are subscriber-specific, in at least one embodiment, the UE 102 uses two or more subscriber identities to facilitate access to the cellular networks of two or more operators. In the illustrated embodiment, this multiple subscriber identity configuration of the UE 102 is implemented via two SIMs 112. SIM 112-1 (“SIM1”) represents a subscriber identity associated with a subscription with network 104-1, and SIM 112-2 (“SIM2”) represents a subscriber identity associated with a subscription with network 104-2. SIMs 112-1 and 112-2 may be implemented, for example, as physical SIMs, virtual SIMs, or a combination thereof.

[0016] Each SIM 112 can be used by the UE 102 to establish a cellular connection with a corresponding network 104 based on a corresponding radio access technology (RAT). Examples of cellular RATs include, but are not limited to, the aforementioned 5G NR, LTE, Global System for Mobile (GSM), and UMTS, as well as single-carrier radio transmission technology (1xRTT), Worldwide Interoperability for Microwave Access (Wi-MAX), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Evolved Data Optimized (EV-DO), etc. In some embodiments, the UE 102 uses a single-SIM mode in which only one SIM is available to the UE 102, and a user can manually switch between SIMs 112 to switch between cellular connections. In another embodiment, the UE 102 uses a standby mode such as Dual SIM Dual Standby (DSDS), in which a single RF resource (e.g., RF transceiver or modem) is shared by both SIMs 112, and the UE 102 alternates between the cellular connection on SIM 112-1 and the cellular connection on SIM 112-2 using time division multiplexing. In yet another embodiment, the UE 102 uses a dual active mode such as Dual SIM Dual Active (DSDA), in which each SIM 112 has its own unique RF resource for the UE 102, allowing both cellular connections to be active simultaneously.

[0017] While facilitating the use of multiple subscriber identities allows the UE 102 to connect to more than one operator, in some situations it may be impractical or impossible to use one of the cellular connections. For example, if the UE 102 roams beyond the air interface range of a base station 110 of a network 104, the UE 102 may be unable to establish any kind of cellular connection with that network 104, or the signal or connection quality of one cellular connection may limit the usefulness of that connection to the UE 102. As another example, the UE 102 may be “roaming” within the coverage area of ​​a secondary network by being located outside the area associated with its primary or “home” mobile network operator, and roaming charges incurred if the UE 102 uses a cellular connection with the secondary network, for example to support voice services, may be prohibitive to the user. In such cases, it may be advantageous to be able to use a suitable cellular connection established for one subscription to support services provided by operators associated with other subscriptions. In conventional UEs, such crossover sharing of cellular connections is prevented by the tight coupling between the subscriber, the software stack of the UE associated with the subscriber, and the operator's service support based on the subscriber identity.

[0018] To address situations where the preferred or “primary” network 104 is out of coverage (OOS) (i.e., where the UE 102 is unable to establish a connection with the primary network 104 or where such a connection is insufficient to provide a call (voice and / or video / audio) of sufficient quality), the UE 102 is configured to use cross-SIM calling. In a cross-SIM calling scenario, assuming the UE 102 can establish a sufficient connection with a non-primary or “secondary” mobile network operator's network 104, the UE 102 can establish a connection with the secondary network 104 through one or more PDNs 105 or other networks connecting the two cellular networks 104. However, as noted above, with traditional cross-SIM calling, there is typically little guarantee that the wireless connection with the secondary network 104 has a sufficient level of QoS support to support the voice / video call, and therefore, traditional cross-SIM calling may be of unacceptable quality due to the initial link between the UE and the secondary mobile network operator.

[0019] To address this, in at least one embodiment, the cellular system 100 leverages network slicing techniques to provide QoS sufficient to support cross-SIM calls. Network slicing, first introduced for 5G NR radio access technology (RAT) and radio access network (RAN), is a network architecture that facilitates virtualization and multiplexing of independent logical networks on the same physical network infrastructure. Each “network slice” is a logically isolated, or “virtual,” end-to-end network tailored to a corresponding set of requirements, such as low latency, guaranteed bandwidth, and support for Internet of Things (IoT) devices with long battery life. A network slice can also have dedicated resources within a single cellular network or across multiple cellular networks. Thus, a network slice can comprise one or more radio access network (RAN) slices and / or one or more core network slices. Of particular importance in the following discussion is the ability of a mobile network operator to provide specific QoS parameters for each slice. For example, a cellular network might offer one network slice supporting high bandwidth, another network slice supporting low latency, and yet another network slice providing near-zero packet drop rates.

[0020] Thus, the UE 102 utilizes network slicing provided by the secondary network to attempt to establish a wireless connection with the secondary network via a network slice with QoS features appropriate for the type of call to be made (this set of one or more QoS features is referred to herein as the “call QoS,” and therefore a network slice supporting such call QoS is referred to herein as the “call QoS slice”). This may include low latency and low packet drop rate for voice calls, or low latency and high throughput for video calls. Once the call QoS slice is established between the UE 102 and the secondary network 104, the UE 102 can establish a network tunnel with the primary network 104 using this call QoS slice and conduct the call using the network tunnel with call-level QoS support for the wireless connection between the UE 102 and the secondary network 104 via the established call QoS slice.

[0021] For purposes of explanation, the following assumes that network 104-1 is the primary network and network 104-2 is the secondary network. In response to UE 102 being unable to establish a connection with primary network 104-1 (OOS state 114) but a software application running on UE 102 attempting to initiate a call (voice or video), UE 102 triggers a cross-SIM call by establishing wireless connection 116 with BS 110-2 of secondary network 104-2 using SIM 112-2 and the subscriber identity represented thereby. As part of this process, secondary network 104-2 can inform UE 102 of various types of network slices available to UE 102 and their associated QoS capabilities. UE 102 can identify a network slice type with a QoS appropriate for the initiating call and request secondary network 104-2 to connect UE 102 to a network slice having the identified network slice type. In another embodiment, the UE 102 notifies the secondary network 104-2 of its call establishment attempt and, possibly, the QoS capabilities required for the call, and the secondary network 104-2 selects a network slice for the UE 102 to use based on this information. In either approach, assuming the secondary network 104-2 authorizes the UE 102 to use the appropriate network slice, the UE 102 and the secondary network 104-2 establish a call QoS slice 118 (which may be extended to the core network 106-2 as a core network slice) for the wireless connection 116 between the UE 102 and a corresponding gateway (e.g., an access point name (APN) gateway 120) in the core network 106-2.

[0022] The UE 102 can then use the SIM 112-1 (and the subscriber identity represented thereby) to establish a network tunnel 122 with the primary network 104-1 over the wireless connection 116 with the secondary network 104-2. In particular, the UE 102 establishes the network tunnel 122 over the call QoS slice 118 established between the UE 102 and the core network 106-2 of the secondary network 104-2, and over the connection between the core network 106-2 and the core network 106-1 of the primary network 104-1 over one or more PDNs 105. The network tunnel 122 may comprise any of a variety of tunnels suitable for providing voice / video call services between the UE and one cellular network over a wireless connection with another cellular network. For purposes of illustration, because network operators typically provide Internet Packet (IP) call services via an IP Multimedia Services (IMS) server, the network tunnel 122 may include an IP Security (IPSec) tunnel, and more specifically, an evolved packet data gateway (ePDG) tunnel established between the UE 102 and an IMS server 124 in the core network 106 via the call QoS slice 118 and one or more PDNs 105. In this approach, the UE 102 uses the SIM 112-1 and its subscriber identity in an authentication process used to authenticate the UE 102 to the IMS server 124 and other components (e.g., edge gateways) of the core network 106-1 when establishing the ePDG tunnel. After the network tunnel 122 is established, the UE 102 and the IMS server 124 or other supporting network components can continue the call establishment process and exchange uplink and downlink data packets to support the established call.

[0023] Thus, using the above techniques, the UE 102 can adapt to the OOS state 114 of the primary network 104-1 by establishing a wireless connection 116 with the secondary network 104-2 using a call QoS slice that provides one or more QoS features suitable for establishing an acceptable level of call QoS, then using the call QoS slice to implement a network tunnel with the primary network 104-1 and conducting the call through the network tunnel. Thus, the UE 102 obtains advantages for conducting the call with the primary network 104-1, including the use of a primary subscriber identity typically associated with the UE 102 and avoidance of call roaming charges. Furthermore, even if the wireless connection is a data connection with the secondary network 104-2, it provides a predictable, and potentially guaranteed, QoS level suitable for the call, which might not otherwise be suitable for conducting voice or video calls.

[0024] 2 illustrates an example hardware configuration of a UE 102 according to some embodiments. In the illustrated example, the UE 102 includes an application processor 202 (e.g., a central processing unit (CPU) or other general-purpose processor), a system memory 204, one or more RF modems 206, one or more RF transceivers 208, and one or more antenna arrays 210 suitable for RF signaling and signal processing in one or more frequency bands typically associated with a corresponding RAT (e.g., a 5G NR RAT).

[0025] The RF modem 206 includes a baseband processor 214 and memory 216, such as flash memory, non-volatile random access memory (NVRAM) or other non-volatile memory, or static RAM (SRAM) or dynamic RAM (DRAM) or other volatile memory, or a combination thereof. The RF modem 206 is connected to two or more SIM interfaces (IFs) 212 (e.g., SIM1IF 212-1 and SIM2IF 212-2) to receive and connect to the SIMs 112-1 and 112-2, respectively. One or both of the SIMs 112-1 or 112-2 can be implemented as virtual SIMs (“eSIMs”), such that the corresponding SIM interface 212 can represent a secure memory location within the UE 102 that stores, for example, the subscriber identity and associated information represented by the virtual SIM. Note that in the illustrated embodiment, the UE 102 is configured to support either a single-SIM mode or a DSDS mode, whereby RF resources (RF modem 206, RF transceiver 208, and antenna array(s) 210) are shared between SIMs 112-1 and 112-2 through time multiplexing when each SIM 112 maintains a cellular connection. In other embodiments, the UE 102 is configured to support a dual-SIM dual-active (DSDA) mode with separate instances of RF resources for each SIM 112, whereby the cellular connections of both SIMs 112-1 and 112-2 can be active simultaneously. Furthermore, it will be understood that the UE 102 may include several additional components, such as one or more displays, one or more touchscreens, a keypad, a mouse, a touchpad, a microphone, a speaker, other user input / output devices, one or more sensors, a battery or other power source, a graphics processing unit (GPU) or other co-processor, etc., which are omitted from FIG. 2 for simplicity of illustration.

[0026] As a general overview of operation, the application processor 202 executes executable instructions from a software stack that includes an operating system (OS) 230 and one or more user software applications, such as user software applications 232, and may also include a protocol stack executed by the RF modem 206. The OS 230, through operation of the application processor 202, manages the general operation of the various hardware components of the UE 102 as well as supports the execution of one or more user software applications. The executable instructions representing the OS 230 and the user software applications are typically accessed from the system memory 204 and executed by the application processor 202. Accordingly, modules of the OS 230 include a cellular module 236 for controlling or facilitating higher-level cellular-related operations of the UE 102, such as subscriber identity management, initiating, controlling, and disconnecting cellular connections, authentication, and interfacing between cellular connections and user software applications. As part of this, cellular module 236 includes a cross-SIM call manager 238 configured to manage certain operations of UE 102 for establishing a cross-SIM call, including establishing a call QoS slice with the secondary network, establishing a network tunnel with the primary network via the call QoS slice, etc. Additionally, memory 216 of RF modem 206 stores a protocol stack 240 for each subscriber identity of UE 102, such as protocol stacks 240-1 and 240-2 for SIMs 112-1 and 112-2, respectively. Each protocol stack 240 stores executable instructions that, when executed by baseband processor 214, operate baseband processor 214 to perform various operations in accordance with the RAT protocol or other communication protocol associated with the air interface provided by base station 110 (FIG. 1) of network 104 with which UE 102 is attempting to establish a communication link.As is well known, such operations are typically associated with the lower layers of a network protocol, such as some or all of the physical, data link, and network layers, while OS 230 and user software applications support the higher layers of a network protocol, such as the transport, session, presentation, and application layers.

[0027] 3 illustrates an example method 300 of operation of system 100 for supporting cross-SIM calls using call QoS slicing in accordance with some embodiments. While method 300 is described with reference to the embodiment of UE 102 shown in FIG. 2, it is not limited to such a configuration and can instead be adapted to any of a variety of configurations of multi-subscriber UEs using the guidelines provided herein. For illustrative purposes, method 300 will be described in the example scenario above, where network 104-1 is the primary cellular network and network 104-2 is the secondary cellular network.

[0028] Method 300 begins at block 302 with user software application 232 initiating a call. For example, user software application 232 may be a voice telephony application used to make voice calls, a chat or video conferencing application used to make voice / video calls, etc. As part of the call initiation, user software application 232 requests a data interface to support the call from cellular phone module 236 of OS 230. In response to this request, at block 304, cellular phone module 236 determines the current connection state with primary network 104-1 using SIM 112-1, and more specifically, whether there is an OOS or other condition that prevents UE 102 from establishing a direct wireless connection with primary network 104-1. If primary network 104-1 is up for UE 102 using SIM 112-1, then at block 306, cellular phone 236 establishes a wireless connection with primary network 104-1 and provides user software application 232 with a network interface for the wireless connection to conduct the call.

[0029] However, if there is an OOS or other condition that prevents a direct wireless connection with the primary network 104-1 from being available to complete the initiated call, then in block 308, the cellular module 236 determines whether the secondary network 104-2 is up and running. If not (assuming only two subscriber identities in this example), then the UE 102 does not have a wireless connection with a cellular network available to support the call, and in block 310, the cellular module 236 reports to the user software application 232 that an error occurred in establishing the data interface for the call. In response, the user software application 232 terminates the attempted call, and the method 300 ends.

[0030] Otherwise, if the secondary network 104-2 is operational and can establish a wireless connection with the UE 102 (if not already established), the UE 102 and the secondary network 104-2 operate to establish a network slice with QoS support for the initiated call (i.e., a call QoS slice) between the UE 102 and the secondary network 104-2. Accordingly, in block 312, a network slice provided by the secondary network 104-2 is selected or identified as the network slice to be used as the call QoS slice. This process can be implemented in various ways. As shown in block 313, this identification process can be performed by the secondary network 104-2. For example, in some embodiments, the secondary network 104-2 may support one or more types of network slices dedicated to cross-SIM calls, and when the cross-SIM call manager 238 sends a connection request to establish a wireless connection between the UE 102 and the secondary network 104-2 using the subscriber identity of SIM 112-2, the connection request or subsequent communication may include, for example, an indication that the connection request is related to a cross-SIM call. In response, the network slicing management component or other component of the secondary network 104-2 can select a network slice specifically designated as suitable for the cross-SIM call and instruct the UE 102 to connect via the selected network slice. Alternatively, the cross-SIM call manager 238 can signal desired QoS parameters for the initiated call, such as a specified maximum delay threshold or a specified minimum throughput level, and the network slicing management component or other component of the secondary network 104-2 can select a network slice that meets or comes closest to meeting the signaled QoS capabilities and then instruct the UE 102 to attempt to connect to the selected network slice.

[0031] Alternatively, as represented by block 315, the UE 102 can identify a network slice to be used as the call QoS slice. In this approach, the secondary network 104-2 can provide the UE 102 with network slice information on an ad hoc basis when the UE 102 camps on the secondary network 104-2 or through prior notification of the secondary network 104-2's network slice configuration (e.g., when the UE 102 is idle). In at least some embodiments, the network slice information consists of a list or other data structure representing available network slices, along with information such as an identifier for each available network slice, device requirements, application / service requirements, QoS capabilities (characteristics), service level agreements (SLAs), configured resources, etc. In some embodiments, the network slices available for use by the UE 102 may be based on a subscriber identity associated with the SIM 112-2. That is, the number / type of network slices made available to the UE 102 may depend on a pre-configured service level associated with the subscriber identity of the SIM 112-2. Among conventional network slice types, the network slice types may further include, for example, one or more cross-SIM call slice types configured to provide specific call QoS parameters that support cross-SIM calls. Alternatively, the network slice types may include network slice types not specifically designed for cross-SIM calls, and the UE 102 may select a network slice type suitable for providing sufficient call QoS for the initiated call. The cross-SIM call manager 238 of the UE 102 may select a supported network slice type, for example, by a priori identifying a network slice type that provides QoS capabilities suitable for the initiated call or by comparing the signaled QoS capabilities for one or more network slice types with the corresponding QoS requirements of the initiated call.For example, the user software application 232 may signal to the cellular phone module 236 that it requires a data interface that provides, for example, a maximum latency of 20 milliseconds (ms) and a minimum instantaneous throughput of 144 kilobits per second, and the cross-SIM call manager 238 may then select an available network slice type that minimally meets these two QoS criteria.

[0032] After the secondary network 104-2 or the UE 102 identifies a particular network slice to serve as the call QoS slice for the initiated call, the cross-SIM call manager 238 coordinates with the protocol stack 240-2, and more generally with the RF modem 206, to request a wireless connection with the secondary network 104-2 using the network slice identified in block 312 (as the call QoS slice) based on the subscriber identity associated with the SIM 112-2, in block 314. In response to the request, the secondary network 104-2 establishes the requested wireless connection (e.g., wireless connection 116 of FIG. 1 ) if it is not already established, and further establishes the requested network slice (e.g., network slice 118 of FIG. 1 ) with the UE 102 in block 316. In response to establishing the wireless connection and the call QoS network slice, at block 318, the cross-SIM call manager 238 establishes a network tunnel (e.g., network tunnel 122 in FIG. 1 ) with the IMS server 124 of the primary network 104-1 based on the subscriber identity provided by the SIM 112-1 using the established wireless connection and call QoS slice with the secondary network 104-2. As described above, this network tunnel may include, for example, an IPSec tunnel, or more specifically, an ePDG tunnel. As explained above, because this network tunnel is established using the subscriber identity of the SIM 112-1, it provides access to various services offered by the primary network 104-1 in association with that subscriber identity, including, for example, various IMS services (e.g., voice over IP (VoIP)) and specific QoS features for the offered services.

[0033] With the network tunnel in place, at block 320, the OS 230 presents a data interface linked to the network tunnel to the user software application 232 for use in conducting the initiated call, and at block 322, the UE 102 conducts the call using the network tunnel associated with the data interface. For example, in the case of uplink communications, data representing the voice and / or video content of the call is provided to the data interface, after which the data is packetized and transmitted to the IMS server 124 via the network tunnel using, for example, a VoIP protocol. This transmission includes transmission via the established call QoS slice between the UE 102 and the BS 110-2 (and potentially to the core network 106-2) using the QoS support associated with the network slice used for the call QoS slice. Similarly, for downlink communications, packetized data representing voice and / or video content is provided from the IMS server 124 via the PDN 105 to the core network 106-2 of the secondary network 104-2, and the packetized data is then transmitted from the secondary network 104-2 to the UE 102 via the established call QoS slice with associated QoS support.

[0034] FIG. 4 illustrates a ladder diagram 400 illustrating an example operation of method 300 according to some embodiments. In this example, user software application 232 sends a data connection request 402 for a data interface used to conduct the call (an example of the call initiation process of block 302). In this example, primary network 104-1 is out of service for UE 102, and secondary network 104-2 is in service for UE 102. Accordingly, UE 102 and / or secondary network 104-2 operate to identify a network slice to utilize as the call QoS slice, as represented by block 404 and described above with reference to blocks 312, 313, and 315 of FIG. 3 . Once the appropriate network slice is identified, cross-SIM call manager 238 instructs protocol stack 240-2 to issue a network slice connection request 406 to secondary network 104-2, possibly providing the subscriber identity of SIM 112-2 for authentication purposes. In response to authenticating the subscriber identity and the availability / suitability of the requested network slice, the network slicing manager or other component of the core network 106-2 sends a connection authorization 408 to the UE 102, and in response, the UE 102 connects to the BS 110-2 and the secondary network 104-2 using the requested network slice (blocks 314 and 316 of FIG. 3). The cross-SIM call manager 238 then instructs the RF modem 206, using the subscriber identity of the SIM 112-1 for authentication purposes, to send an ePDG tunnel request 410 to the primary network 104-1 over a wireless connection with the secondary network 104-2, and the primary network 104-1 authenticates the subscriber and responds with an ePDG tunnel grant 412 that is sent to the UE 102 over the secondary network 104-2 (block 318 of FIG. 3). In response to notification that the ePDG tunnel has been initiated, the cellular module 236 issues a connection grant 414 to the user software application 232. The connection permission 414 indicates the network interface details (port, destination IP address, etc.) (block 320 of FIG. 3).In response to the connection authorization 414, the user software application 232 sends and receives VoIP traffic 416 via the established data interface, the associated ePDG tunnel, and the call QoS slice supporting the portion of the ePDG tunnel extended between the UE 102 and the secondary network 104-2.

[0035] In some embodiments, certain aspects of the techniques described above are implemented by one or more processors of a processing system executing software. The software includes one or more executable instruction sets stored or otherwise tangibly embodied on a non-transitory computer-readable storage medium. The software may include instructions and specific data that, when executed by one or more processors, operate the one or more processors to perform one or more aspects of the techniques described above. The non-transitory computer-readable storage medium may include, for example, a magnetic or optical disk storage device, a flash memory, a cache, a solid-state storage device such as random access memory (RAM), or other non-volatile memory device or devices. The executable instructions stored on the non-transitory computer-readable storage medium may be source code, assembly language code, object code, or other instruction formats that can be interpreted or otherwise executed by one or more processors.

[0036] A computer-readable storage medium includes any storage medium or combination of storage media that can be accessed by a computer system during use to provide instructions and / or data to the computer system. Such storage media may include, but are not limited to, optical media (e.g., compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs), magnetic media (e.g., floppy disks, magnetic tape, or magnetic hard drives), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or flash memory), or microelectromechanical systems (MEMS)-based storage media. A computer-readable storage medium may be incorporated into a computing system (e.g., system RAM or ROM), fixedly attached to a computing system (e.g., a magnetic hard drive), removably attached to a computing system (e.g., an optical disk or universal serial bus (USB)-based flash memory), or coupled to a computer system via a wired or wireless network (e.g., network-accessible storage (NAS)).

[0037] In addition to what is described, it should be noted that not all operations or elements described above in the general description are required, and that some of the specific operations or devices may not be required, and that one or more additional operations may be performed or one or more additional elements may be included. Furthermore, the order in which operations are listed is not necessarily the order in which they are performed. Also, concepts have been described with reference to specific embodiments. However, those skilled in the art will recognize that various modifications and variations can be made without departing from the scope of the present disclosure, as set forth in the claims below. Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0038] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, benefits, advantages, and solutions to problems, as well as any feature or features that may cause or make any benefit, advantage, or solution more pronounced, should not be construed as critical, necessary, or essential features of any or all claims. Moreover, the specific embodiments disclosed above are illustrative only, as the disclosed inventive subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to the details of construction or design herein shown, other than as set forth in the claims below. It is therefore apparent that the specific embodiments disclosed above may be altered or modified, and that all such variations are contemplated within the scope of the disclosed inventive subject matter. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

1. 1. A method performed by a user equipment (UE) for conducting a call between the UE and a first cellular network via a second cellular network, the method comprising: and in response to a state of a connection between the UE and the first cellular network being unsuitable for the call, implementing a network slice between the UE and the second cellular network, the network slice having at least one Quality of Service (QoS) function suitable for supporting the call, the method further comprising: establishing a network tunnel between the UE and the first cellular network via the network slice; and packetizing data of the call between the UE and the first cellular network via the network tunnel.

2. 2. The method performed by the user equipment of claim 1, further comprising selecting the network slice from a plurality of network slices obtained from the second cellular network for use by the UE.

3. 3. The method performed by the user equipment of claim 2, wherein selecting the network slice comprises selecting the network slice at the UE based on a list of available network slices provided by the second cellular network.

4. 4. The method performed by the user equipment of claim 3, wherein selecting the network slice further comprises selecting the network slice based on a comparison of QoS parameters of the call and corresponding QoS capabilities of one or more available network slices.

5. establishing the network tunnel includes establishing the network tunnel based on a first subscriber identity of the UE associated with the first cellular network; A method performed by a user equipment as described in any of claims 2 to 4, wherein the plurality of network slices obtained from the second cellular network for use by the UE are based on a second subscriber identity of the UE associated with the second cellular network.

6. 6. The method performed by a user equipment according to claim 1, further comprising receiving, at the UE, an indication of the network slice to be implemented from the second cellular network in response to at least one of: sending an indication of at least one QoS requirement of the call to the second cellular network; or sending an indication that the call should be supported by the first cellular network via the second cellular network.

7. establishing the network tunnel includes establishing the network tunnel based on a first subscriber identity of the UE associated with the first cellular network; A method performed by a user equipment according to any one of claims 1 to 6, wherein implementing the network slice comprises implementing the network slice based on a second subscriber identity of the UE associated with the second cellular network and different from the first subscriber identity.

8. the first subscriber identity is stored by a first subscriber identity module (SIM) of the UE; The user equipment performed method of claim 7 , wherein the second subscriber identity is stored by a second SIM of the UE.

9. A method performed by a user equipment as described in any one of claims 1 to 8, wherein establishing the network tunnel includes establishing the network tunnel between the UE and an Internet Protocol Multimedia Services (IMS) server of the first cellular network.

10. initiating the call on the UE by a user software application executing on the UE; 10. The method performed by a user equipment of claim 1, further comprising: providing a data interface for use in the call to the UE in response to establishing the network tunnel.

11. 1. A method performed by a user equipment (UE), comprising: performing a cross-subscriber identity module (cross-SIM) call between a user equipment (UE) and a first cellular network via a network tunnel between the UE and a first cellular network utilizing a network slice established between the UE and a second cellular network depending on a state of a connection between the UE and the first cellular network, wherein the network slice is selected to provide at least one quality of service (QoS) feature supporting the cross-SIM call.

12. 12. The method performed by the user equipment of claim 11, wherein the second cellular network selects the network slice based on the UE attempting to perform the cross-SIM call.

13. 12. The method performed by the user equipment of claim 11, wherein the UE selects the network slice from the list of network slices obtained from the second cellular network based on QoS capabilities supported by the listed network slices.

14. The method performed by a user equipment according to any one of claims 1 to 13, wherein the network tunnel comprises an evolved packet data gateway (ePDG) tunnel.

15. A method performed by a user equipment according to any preceding claim, wherein the call comprises one of a voice call or a video call.

16. an application processor; a radio frequency (RF) modem connected to the application processor; at least one antenna array connected to said RF modem; and at least one memory for storing instructions, the instructions configured to operate one or both of the application processor or the RF modem to perform a method according to any preceding claim.

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